This invention relates to RFID or radio frequency identification applications. More specifically, the invention relates to identifying particular items when there are a multitude tags on containers of objects in the field of the RFID tag reader.
RFID has become a pervasive technology for tracking and identifying people, vehicles, retail items, pallets etc. One of the frequent applications of RFID is that of tracking pallets as they move past a tag reader or xe2x80x98base stationxe2x80x99. Generally pallets as used in industry contain a large number of individual boxes or crates. Each crate may contain an individual, unique RFID tag. The tag may contain generic or even detailed data relating to the contents of the crate. However, present day tag readers cannot distinguish between or amongst the multitude of tags that are presented in the field. Thus, while all the tags are read in a sequential manner, the reader output cannot distinguish which tag corresponds to the particular package or crate. This lack of correlation between the tag reader and the crate makes it impossible to know which crate to unload at a particular location unless all the crates and their contents are identical. In those cases where the crates are not all identical in content, it becomes necessary to scan each tag individually in order to know which crate to unload, a time consuming and impractical solution to today""s methods of distribution.
However, the prior art does not disclose ways that accurately and simply correlate information obtained by reading one or more tags to the specific location of the respective tag. In particular, the correlation of information and position of tag objects is not disclosed in the art related to inventory control or processing containers and/or contents in those containers.
It is the object of this invention to modify the conventional method of scanning RFID tags to correlate tag information with tag/object position of each tagged object and/or separately packaged item (in a container). It is another object of this invention to modify the conventional method of scanning RFID tags to correlate tag information with tag/object position of each tagged object and/or separately packaged item (in a container) on pallets.
The present invention comprises a base station system for communicating with radio frequency tags attached to one or more objects. The base station has one or more computers, each having one or more central processing units (CPUs) and one or more memories. A separate position detector determines the position of one or more of the tags within a time increment and within a field of the base station. A communication process, executed by one or more of the CPUs, reads information from one or more of the tags within the time increment and associates the position determined with the information of the respective tag in one or more of the memories.
In one embodiment of the invention a movable or non-stationary base station antenna providing a narrow tag interrogation beam is used as the position detector. The reflected wave from the tag may also be narrow though this is not required. The antenna of the reader is designed to have rotational motion to allow for scanning in a vertical plane. Scanning can then be accomplished as a function of position with the antenna scanning vertically while the object (e.g. pallet) moves horizontally. In this mode of scanning, each tag is scanned individually as it passes the base station antenna so that the combination of horizontal pallet motion with vertical scanning results in an xy coordinate associated with each tag readout. The horizontal motion ( x direction) can be determined by knowing the velocity of the object (pallet). This can be accomplished by way of a photocell as the pallet enters a given position and exits a second position together with the knowledge of the time interval between the two photo signals. Stationary pallets can also be scanned by an antenna which can have motion in both x and y directions. Scanning can also be accomplished with fixed or stationary antenna by using a laser beam that scans and turns on individual tags for a brief time. In that case, a wide field antenna is preferably used.